This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Diffuse Optical Imaging and Spectroscopy (DOI, DOS) are emerging diagnostic techniques that quantitatively measure the concentration of deoxy-hemoglobin, oxy-hemoglobin, water, and lipid in cm-thick tissues. In early-stage clinical studies, DOI and DOS have been used to characterize breast tumor biochemical composition and monitor therapeutic response in neoadjuvant chemotherapy patients. In this work, we investigate whether DOS measurements obtained early in a neoadjuvant chemotherapy regimen can predict final, post-surgical pathological response in breast cancer patients.